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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Convergence of oscillator spectral estimators for counted-frequency measurements.

A common intermediary connecting frequency-noise calibration or testing of an oscillator to useful applications is the spectral density of the frequency-deviating process. In attempting to turn test data into predicts of performance characteristics, one is naturally led to estimation of statistical values by sample-mean and sample-variance techniques. However, sample means and sample variances themselves are statistical quantities that do not necessarily converge (in the mean-square sense) to actual ensemble-average means and variances, except perhaps for excessively large sample sizes. This is especially true for the flicker noise component of oscillators. This article shows, for the various types of noises found in oscillators, how sample averages converge (or do not converge) to their statistical counterparts. The convergence rate is shown to be the same for all oscillators of a given spectral type.

Tausworthe, R. C.↗
NASA NTRS1973

Method of detecting and counting bacteria in body fluids

A novel method is reported for determining bacterial levels in urine samples, which method depends on the quantitative determination of bacterial adenosine triphosphate (ATP) in the presence of non-bacterial ATP. After the removal of non-bacterial ATP, the bacterial ATP is released by cell rupture and is measured by an enzymatic bioluminescent assay using an enzyme obtained from the firefly.

Chappelle, E. W.↗
NASA NTRS1973

An electrophotometer operating in a photon-counting regime

A photon counter photometer constructed allows one to carry out the UBV - photometry of stars from 6.0 to 14.0 stellar magnitude with the accuracy of 0.007 to 0.017 stellar magnitude. The absorption coefficients in U, B, V are determined and the color equations for transferring the observed magnitude differences to the UBV system are found.

Pugach, A. F.↗
NASA NTRS1973

Photon counting with a self-scanned diode array.

A self-scanned diode array may be used as temporary storage for individual photons if enough gain is provided by an image intensifier or electron multiplier to provide a detectable signal from each input event.

Mcnall, J. F.↗
NASA NTRS1974

Improved methods for counting bacteria in physiological fluids

Bacterial population detection is based on detection of adenosine triphosphate (ATP), chemical present in all living matter. Amount of ATP in sample, after chemically removing all nonbacterial ATP, is directly related to bacterial population. Sensitivity is improved by concentration step; specificity is improved by lowering pH of solution.

Picciolo, G. L.↗
NASA NTRS1975

On a photon-counting array using the Fairchild CCD-201

The evaluation of certain performance parameters of the Fairchild CCD 201 and the proposed method of operation of an electron bombarded charge coupled device are described. Work in progress on the evaluation of the parameters relevant to remote, low noise operation is reported. These tests have been conducted using light input. The video data from the CCD are amplified, digitized, stored in a minicomputer memory, and then recorded on magnetic tape for analyzing. The device will be used in an array of sensors in the aperture plane of a telescope to discriminate between photoelectron events, and in the focal plane operating at single photoelectron sensitivity at a minimum of blooming and lag.

Currie, D. G.↗
NASA NTRS1977

Counting digital filter

Overall design of filter combines radix converter with ADC in single functional unit that directly converts analog input to its negative binary representation. Four basic elements of filter are fixed register, shift register, counter, and accumulator.

Zohar, S.↗
NASA NTRS1976

Photoelectron counting with an image intensifier tube and a self-scanned photodiode array

A self-scanned photodiode array was fiber-optically coupled to an ITT proximity-focused image intensifier tube. It was determined that a single photoelectron event produces 34,000 charge carriers in a photodiode. This charge is only a factor of 2.8 above the rms noise level of the preamplifier used in the tests, but standard charge-sensitive techniques are at least a factor of 12 better. The image tube and photodiode array combination can be packaged in a disk 5.1 cm in diameter and 2.6 cm thick.

Sandel, B. R.↗
NASA NTRS1977

Photon counting processor for laser velocimetry

In some of the more difficult applications of laser Doppler velocimetry such as in combustion research, transonic flow, transverse wind, and others, the optical signals are too small for classical detection methods. This paper summarizes the theory, experimental prototype hardware, and test results for a new type of high-speed photon-correlation signal processor which is being developed for weak laser velocimeter signals and other photon-resolved signals. The new system may also be considered to be a statistical digital frequency discriminator. It uses full multiplication with 10-nsec delay time and has the potential for extension to the measurement of the velocity correlations and spectra.

Mayo, W. T., Jr.↗